validation of a new brief five-item measure of satisfaction ...... ment plan, treatment steps and the outcome. Accord- ing to our research, the absence of tooth ...
International Dental Journal
SCIENTIFIC RESEARCH REPORT
doi: 10.1111/idj.12362
Smile Aesthetics Satisfaction Scale: development and validation of a new brief five-item measure of satisfaction with smile aesthetics in adults and the elderly Vlatka Lajnert1, Daniela Kovacevic Pavicic1, Andrej Pavlic2, Alessandra Pokrajac-Bulian3 and Stjepan Spalj2 1 Department of Prosthodontics, Dental School, Faculty of Medicine, University of Rijeka, Rijeka, Croatia; 2Department of Orthodontics, Dental School, Faculty of Medicine, University of Rijeka, Rijeka, Croatia; 3Department of Psychology, Faculty of Humanities and Social Sciences, University of Rijeka, Rijeka, Croatia.
Objective: To create and validate a brief questionnaire designed for the assessment of satisfaction with smile aesthetics and to test its efficiency as a patient-centred outcome measure of aesthetic interventions in dentistry. Materials and methods: A team of three specialists – two from prosthodontics and one psychologist – used a self-evaluation scale consisting of five elements in order to rate self-perceived smile aesthetics. A total of 671 subjects (63% female), 18–86 years of age, were included in the investigation. The internal consistency, validity and stability of the questionnaire, along with the responsiveness induced by the tooth-whitening procedure, were evaluated. The relationship between self-perceived satisfaction with the smile aesthetics and the clinical status of the dentition was assessed. Results: The questionnaire had one dimension accounting for 64.3% of variance and showed a high level of reliability (Cronbach a = 0.859). It measured a construct similar to concern with tooth appearance and the desire to improve this appearance (r = 0.403 and r = 0.353, respectively; P < 0.001). High test–retest reliability was demonstrated (intraclass correlation coefficient = 0.985). The questionnaire was able to detect an increase in satisfaction with smile aesthetics as a result of the tooth-whitening procedure (P = 0.016). Clinical predictors of greater satisfaction with smile aesthetics were greater tooth display when smiling, decreased chroma and the absence of gingivitis, as well as absence of crowded, fractured and restored teeth in the anterior segment. Conclusions: A new questionnaire, titled the Smile Aesthetics Satisfaction Scale (SASS), showed good psychometric properties and its use can be recommended. Key words: Dental aesthetics, psychometrics, quality of life, reliability, validity
INTRODUCTION Facial aesthetics and physical appearance have great potential to affect one’s social life. Self-perceived facial appearance is frequently related to concern regarding other people’s opinions and reactions. Therefore, even small imperfections in dental aesthetics might lead to a fear of negative public reactions and cause appearance-based insecurity1. Appearance of lips and teeth are two main characteristics that define the overall facial appearance. Investigations that analysed eye movements in face-toface interactions showed that the eyes of the observer primarily focus on the other person’s eyes, mouth and © 2018 FDI World Dental Federation
perioral region, while just a small fraction of time is spent observing other facial characteristics2. Observers are often inclined to attribute more pleasing characteristics to those who have aligned teeth than to those with imperfections in tooth alignment3,4. Poorer dentofacial appearance may result in negative connotations by the observer regarding one’s personality and psychological characteristics, whereas individuals with a more attractive dental and smile appearance are often perceived as socially more competent and psychologically more adaptive, as well as eventually viewed as more intelligent2,4. Patients’ self-reports on the elements of aesthetics that are a source of major concerns are of key importance to the clinician and 1
Lajnert et al. enable her/him to form a treatment strategy. There are many questionnaires published in the literature that aim to assess particular characteristics and features of the patient, dimensions of their personality and the perception of dentofacial aesthetics. The large number of variables makes it difficult to obtain an adequate number of accurate responses owing to the time it takes to fill out such a questionnaire. Furthermore, clinicians need a significant amount of time to process the data obtained, which in turn significantly reduces the time spent on communicating with patients. Therefore, the aim of this investigation was to create a new psychometric instrument that would be simple and brief, without losing its reliability in assessment of what is important to patients when restoring deteriorated smile aesthetics, primarily through prosthetic rehabilitation. Our assumption is that the new instrument will be one dimensional, have a high internal consistency and measure the construct similar to dental self-confidence, aesthetic concern and the desire to improve the smile appearance. In addition, we hypothesised that crowded and dark-colored teeth will be the source of greatest facial dissatisfaction. The questionnaire will have good stability throughout the period with no dental intervention. It will be able to detect changes in patient satisfaction from aesthetic dental interventions, such as tooth whitening. MATERIALS AND METHODS The initial idea of this new questionnaire was to create a short scale for assessment of satisfaction with smile aesthetics, which would detect the exact aesthetic component and the extent to which it causes concern among patients. A three-member team, comprising two specialists in prosthodontics and one psychologist, was formed, with the initial list of the elements of dentofacial aesthetics agreed upon based on their experience and a literature review. In order to rank the self-perceived satisfaction with smile aesthetics (formulated as: ‘Are you satisfied with. . .?’), self-assessment in relation to five elements (tooth appearance, tooth colour, tooth shape, tooth position/ alignment and the appearance of the gingiva) was used via a three-point Likert scale (1 = not satisfied, 2 = moderately satisfied and 3 = completely satisfied). This type of scale was chosen as it offers clarity and patients understand them better than scales with more points. In a cross-sectional study, an initial sample of 700 Caucasian subjects (439 female), 18–86 years of age, were recruited among patients who visited the Dental Clinic of the University Medical Centre in Rijeka for regular check-ups or dental treatment, patients scheduled for regular health controls at the Public Health 2
Centre and blood donors from the Transfusion Medicine Center. As a result of missing data, 29 subjects were excluded. In the final analysis, 671 subjects (63% female), 18–86 years of age (median age: 45 years, interquartile range: 30–61 years), were included. All subjects had six maxillary anterior teeth present (intact teeth, colour-matched composite restorations, veneers or crowns), while the exclusion criteria applied were: untreated periodontal disease; caries lesions; significant occlusal wear; active orthodontic treatment with fixed edgewise appliances; participants undergoing prosthetic rehabilitation and thus currently fitted with temporary crowns; participants undergoing endodontic treatment; participants with splints for the treatment of temporomandibular disorders; and participants with craniofacial syndromes. The sample size was based on recommendations for factor analysis, which regard 500 subjects as very good and 1,000 subjects as excellent5. It was also calculated that 650 subjects would be a sufficient sample size for exploring the relationship between a new psychometric instrument and 12 smile aesthetics predictors in hierarchical multiple regression using the following parameters: anticipated small effect size of Cohen’s f 2 = 0.02; power b = 0.8; probability level a = 0.05; and two steps (seven predictors in the first step and five in the second). Taking dropouts into account, it was decided to recruit 700 participants. Clinical examination performed by the single examiner (VL) measured the height and width of the maxillary anterior teeth using a precise calliper (Fowler Ultra; Swiss Instruments Limited, Mississauga, ON, Canada), as well as tooth and gingival display in a posed smile. The plaque score was measured using the method of Silness and Loe6. The following features were noted: existence and type of restoration (healthy tooth without filling(s); composite filling(s); ceramic veneer; faceted crown; metal ceramic crown; and full ceramic crown), and fracture marks on the upper anterior teeth and crowded teeth7,8. Subjects selfreported the presence of bleeding gums (on a scale from 1 = never to 4 = always). Tooth colour was assessed by a single examiner (VL) using the Chromascop Shade Guide (Ivoclar Vivadent, Schaan, Liechtenstein). In order to test the examiner’s accuracy, colour evaluated according to the guide was compared with the colour obtained using a spectrophotometer (Spectroshade Micro; MHT, Verona, Italy) on the sample of 31 subjects, with the weighted Cohen’s kappa (jw) being 0.737 [95% confidence interval (95% CI): 0.525–0.949], indicating good accuracy. The same measurements were repeated on the same subjects after 1 week, and the jw was 0.821 (95% CI: 0.635–1.000), indicating very good precision. All the Chromascop Shade Guide colours were screened using a spectrophotometer in order to © 2018 FDI World Dental Federation
Smile Aesthetics Satisfaction Scale quantify the lightness and chroma, while only CIE L*a*b* values were used for statistical analysis9. L* was used as a measure of lightness, while chroma values were calculated using the formula C* = [(a*)2 + (b*)2]1/2. Accuracy and precision of the spectrophotoshade was checked by comparison with the standard Chromascop Shade Guide and by repeated measurements, then quantified by measurement of intraclass correlation coefficients (ICCs). Validation of a new psychometric instrument was performed according to the criteria set out in the Consensus-based Standards for the Selection of health status Measurement Instruments (COSMIN)10,11. Structural validity was evaluated by exploratory factor analysis and principal component analysis with Varimax rotation. Internal consistency was tested using Cronbach’s alpha and inter-item correlations, while convergent validity as a measure of construct validity was assessed using Pearson and point-biserial correlations. For the purpose of comparison, validated Croatian versions of the Oral Health-Related Quality of Life (OHRQoL) instruments, namely the Oral Impacts on Daily Performance (OIDP) and the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ), were used12,13. In addition, convergent validity was tested by analysing correlations with the answers to questions pertaining to patient concerns over tooth appearance (hiding the teeth when smiling: 0 = no, 1 = yes), self-perceived elements of appearance and the position of the maxillary anterior teeth, and the desire expressed for general improvement in tooth appearance, tooth whitening and orthodontic treatment. The ability of the instrument to detect differences between subjects with and without crowding, tooth fractures and restorations present was tested using the Independent Samples t-test. Responsiveness testing, performed by the Paired Samples t-test in 19 subjects, evaluated whether the new instrument could detect changes induced by in-office tooth whitening with photoactivated whitening gel containing 38% hydrogen peroxide (Signal Easy Lamp Plus and Signal Fast professional plus set, Signal; Unilever, Buenos Aires, Argentina), for 30 minutes. Tooth colour was assessed by spectrophotometry before and after the whitening procedure, with the difference caused by whitening calculated using the formula DE* = (DL*2 + Da*2 + Db*2)1/2. Test–retest reliability was assessed by ICCs; measurement error was evaluated by repeating the assessment of tooth color in 30 subjects within a 1-week interval of the first measurement, without any dental intervention. Hierarchical multiple linear regression analysis was used to assess the predictive value of clinical predictors of the satisfaction with smile aesthetics. All statistical analyses were performed using the commercially © 2018 FDI World Dental Federation
available IBM SPSS 22 software (IBM Corp., Armonk, NY, USA), with the level of statistical significance set at P < 0.05. This investigation was approved by the Ethics Committee of the Medical Faculty University of Rijeka and the Ethics Committee of the University Medical Centre in Rijeka, and was conducted in full accordance with World Medical Association Declaration of Helsinki. Signed, informed consent was obtained for all subjects. RESULTS The distribution of subjects regarding the level of education was as follows: elementary school education, 5.4%; high school graduates, 72.3%; bachelor’s degree, 3.7%; and higher university degree, 18.6%. Distribution of tooth colour and dental status of the subjects is listed in Tables 1 and 2. Factorial analysis demonstrated that this specific scale, based on the assessment of five elements of satisfaction, was one dimensional, thereby measuring general satisfaction with smile aesthetics, and may be used as a summary score of answers to all five items. Principal component analysis extracted one factor, which accounted for 64.3% of variance in all manifested variables. Each item had rather high saturation at the first principal component (0.720–0.870). Elements of the questionnaire showed strong reliability in terms of internal consistency (Cronbach a = 0.859), while the mean correlation among the elements was 0.551 (range: 0.441–0.687). An increase in internal consistency could not be produced by eliminating any item. The name chosen for this instrument was the Smile Aesthetics Satisfaction Scale (SASS); on this scale, values range from a score of five to a maximum of 15. Table 1 Colour distribution Colour according to the Chromascop Shade Guide 120 140 220 230 130 210 240 330 310 530 340 410 430 520 320 420 440 510 Total
n
%
106 42 28 20 165 52 17 6 73 4 14 49 30 5 6 45 8 1 671
15.8 6.3 4.2 3.0 24.6 7.7 2.5 0.9 10.9 0.6 2.1 7.3 4.5 0.7 0.9 6.7 1.2 0.1 100.0 3
Lajnert et al. Table 2 Overview of the dental status of study subjects for a particular tooth Tooth 13 12 11 21 22
n % n % n % n % n %
23 %
Intact tooth
Composite filling
Composite veneer
Ceramic veneer
Faceted crown
Metal ceramic crown
Full ceramic crown
401 59.8 336 50.1 340 50.7 337 50.2 350 52.2 411 61.3
77 11.5 134 20 117 17.4 133 19.8 131 19.5 75 11.2
0 0 0 0 1 0.1 1 0.1 0 0 0 0
0 0 1 0.1 1 0.1 0 0 0 0 0 0
96 14.3 94 14 96 14.3 93 13.9 97 14.5 98 14.6
90 13.4 96 14.3 98 14.6 89 13.3 86 12.8 83 12.4
7 1 10 1.5 18 2.7 18 2.7 7 1 4 0.6
The new questionnaire measures the construct similar to discomfort caused by tooth appearance (hiding one’s teeth when smiling), self-perceived alteration in smile aesthetics (poor tooth restorations and misalignment) [r = 0.403 ( 0.379)], as well as the desire to improve tooth appearance in general, specifically through whitening procedures, or orthodontic or prosthetic therapy [r = 0.353 ( 0.268)] (P < 0.05; Table 3). All correlations were weak, as were correlations between the questionnaire and clinical parameters (Table 3). However, it was possible to differentiate, using the questionnaire, subjects with fractured upper anterior teeth from those without such an impediment (11.9 2.9 vs. 10.5 3.2; P < 0.001), subjects with and without crowding (11.9 2.9 vs. 11.0 3.1; P < 0.001) and subjects with intact teeth from those with restorations (12.3 2.6 vs. 11.2 3.1; P < 0.001). High test–retest reliability was found (ICC = 0.985; Table 4) with small measurement error and small mean value of paired differences. When considering the sample size, the percentage of differences between the test and the retest was appropriate within the limits of agreement. The SASS was demonstrated to be an adequate tool for detecting change in satisfaction with smile aesthetics as a result of the tooth-whitening procedure (P = 0.016), particularly in satisfaction with tooth colour (P < 0.001). However, the degree of colour change did not show a linear correlation with the increase in patient satisfaction (Table 5). Clinically measurable elements of smile aesthetics accounted for a mere 15.4% of variability in satisfaction when smiling. Satisfaction increased with greater tooth display, i.e. larger proportion of teeth displayed when smiling and lower chroma, and in patients with healthy maxillary anterior teeth without the signs of crowding, fracture or gum disease. The most significant unique contribution was demonstrated by crowding and chroma (3% each) and the existence of fractures, tooth restorations and gum disease (2% 4
each), while tooth display when smiling accounted for 1%. Other elements evaluated (lightness, uneven tooth colour, tooth shape, gingival display when smiling, age, gender and education level) were not found to be significant predictors of satisfaction. Hierarchical regression analysis was performed in six steps, in a stepwise manner: the order in which hypothetical predictors were entered started with crowding and fracture in the first step, followed by gingivitis and plaque in the second, the presence of restoration-free teeth in the third, colour elements in the fourth, tooth display when smiling, gingival display and tooth shape in the fifth, and age, gender and level of education in the sixth. This stepwise method enabled the inclusion of only statistically significant predictors, adhering to the principle to include previously defined hypothesised predictors, while reducing the overall number of predictors (Table 6). DISCUSSION The SASS is a good, short, clear and easily understood assessment scale, which points to the level of satisfaction with smile aesthetics. Moreover, it is a good patient-centred outcome measure of aesthetic interventions in dentistry. The validation process was performed according to international criteria, thereby guaranteeing the quality of the psychometric instrument. The SASS is one dimensional and measures general patient satisfaction with tooth and gingival appearance through several elements, which are most visible during interpersonal communication and social interactions. The scale has a 10-point range, from five to 15. It takes
